Many communication receivers use one or more low-noise amplifiers (LNAs) at the front end of the receiver (e.g., close to an antenna) to amplify weak signals received from the antenna or the cable. The LNA can play a role in reducing the effect of the noise generated by the subsequent stages of the receive chain, as these noises are reduced by the gain of the LNA. Therefore an LNA may be required to contribute as little as possible to the noise and signal distortion, while boosting the gain of the receive chain. Various wideband applications such as satellite set-top-boxes (STBs), satellite outdoor units (ODUs), IP low-noise block (IP-LNB) tuners, cable tuners, and MoCA tuners may need radio-frequency (RF) programmable gain and single-end-to-differential conversion that can be implemented before or as a part of a wideband LNA.
Existing solutions include off-chip and on-chip balun circuits that may suffer from a number of drawbacks. For instance, they can be costly, may have difficulty in supporting a wide frequency range, may lack sufficient common-mode/supply rejection and second order distortion performance, may not be sufficiently compact, may have an insertion loss (e.g., 1 dB), and/or may not support differential mode signaling.